It is likely that packet-oriented data traffic will increase exponentially in the next few years, driven by Internet applications, whereas the market for landline network-connected telephony will continue to grow slowly. This means that an increased demand for, by way of example, methods for the automatic routing of optical data packets in the field of optical packet processing is foreseeable for the near future.
In existing and future optical transmission systems, and particularly in transmission systems using Wavelength Division Multiplexing (“WDM”), data is transmitted in the form of data packets using an optical signal. The data packets may comprise various signal types and signal formats, and, specifically when WDM is used, may be allocated to the individual data packets of a plurality of transmission channels. The signal types and signal formats can differ both in terms of the protocol used and/or of the data transmission rates used. Examples of these include Asynchronous Transfer Mode, Internet Protocol (“IP”) and Gigabit Ethernet.
In order to make the best use of the transmission bandwidth available for optical transmission, it is particularly desirable to be able to use an optical data packet stream to transmit a plurality of different signal types and to forward them on a connection-specific basis. To this end, optical transmission systems produced to date usually use a continuous, packet-oriented signal structure that also supports the optical transparency of the optical transmission system. Furthermore, particular requirements of the use of such a signal structure include that the packet-oriented signal structure used is compatible with existing optical transmission systems and transmission equipment, and that the data packets can be forwarded on a connection-specific basis in the respective optical transmission equipment.
To perform automatic routing of optical data packets in transmission systems produced to date, the optical data packet is first optoelectrically converted in optical switching equipment and the electrical data packet header is then used to ascertain the route information associated with the respective data packet. The ascertained route information is used to switch either the data packet represented by an electrical data signal or the electro-optically converted data packet represented by an optical data signal. This presupposes opto-electro-optical conversion of the optical data signal or of the optical data packet stream in the optical transmission equipment in which the data packets are switched.
In addition, purely optical packet switching systems are known in which, by contrast with data systems produced to date, optical data packets are switched exclusively by optical transmission equipment. In this context, the optical data packet has an optical data packet header that is optically processed by the respective optical switching equipment on a bit-by-bit basis. The switching information obtained from the optical data packet header using an enormous amount of technical complexity is used to switch the associated optical data packet in the switching equipment. However, particularly on account of the high transmission rates in the gigahertz range that are customary for optical transmission systems, the implementation of purely optical automatic routing methods of this type requires a considerable level of optical circuit complexity and a high level of optical memory complexity, which causes considerable implementation difficulties in practice.